See the built-in command description in
the appropriate shell manual page.

DESCRIPTION

Shell builtin commands are commands that
can be executed within the running shell’s process. Note
that, in the case of csh(1) builtin commands, the command is
executed in a subshell if it occurs as any component of a pipeline
except the last.

If a command specified
to the shell contains a slash ‘/’, the shell will not
execute a builtin command, even if the last component of the
specified command matches the name of a builtin command. Thus,
while specifying ‘‘echo’’ causes a builtin
command to be executed under shells that support the echo
builtin command, specifying ‘‘/bin/echo’’
or ‘‘./echo’’ does not.

While some builtin
commands may exist in more than one shell, their operation may be
different under each shell which supports them. Below is a table
which lists shell builtin commands, the standard shells that
support them and whether they exist as standalone utilities.

Only builtin commands
for the csh(1) and sh(1) shells are listed here. Consult a
shell’s manual page for details on the operation its builtin
commands. Beware that the sh(1) manual page, at least, calls some
of these commands ‘‘built-in commands’’ and
some of them ‘‘reserved words’’. Users of
other shells may need to consult an info(1) page or other sources
of documentation.

Commands marked
‘‘No**’’ under External do exist
externally, but are implemented as scripts using a builtin command
of the same name.

Command

Externalcsh(1)mksh(1)
! No No Yes
% No Yes No
. No No Yes
: No Yes Yes
@ No Yes Yes
{ No No Yes
} No No Yes
alias No** Yes Yes
alloc No Yes No
bg No** Yes Yes
bind No No Yes
bindkey No Yes No
break No Yes Yes
breaksw No Yes No
builtin No No Yes
builtins No Yes No
case No Yes Yes
cd No** Yes Yes
chdir No Yes Yes
command No** No Yes
complete No Yes No
continue No Yes Yes
default No Yes No
dirs No Yes No
do No No Yes
done No No Yes
echo Yes Yes Yes
echotc No Yes No
elif No No Yes
else No Yes Yes
end No Yes No
endif No Yes No
endsw No Yes No
esac No No Yes
eval No Yes Yes
exec No Yes Yes
exit No Yes Yes
export No No Yes
false Yes No Yes
fc No** No Yes
fg No** Yes Yes
filetest No Yes No
fi No No Yes
for No No Yes
foreach No Yes No
getopts No** No Yes
glob No Yes No
goto No Yes No
hash No No Yes
hashstat No Yes No
history No Yes No
hup No Yes No
if No Yes Yes
jobid No No Yes
jobs No** Yes Yes
kill Yes Yes No
limit No Yes No
local No No Yes
log No Yes No
login Yes Yes No
logout No Yes No
ls-F No Yes No
nice Yes Yes No
nohup Yes Yes No
notify No Yes No
onintr No Yes No
popd No Yes No
printenv Yes Yes No
pushd No Yes No
pwd Yes No Yes
read No** No Yes
readonly No No Yes
rehash No Yes No
repeat No Yes No
return No No Yes
sched No Yes No
set No Yes Yes
setenv No Yes No
settc No Yes No
setty No Yes No
shift No Yes Yes
source No Yes No
stop No Yes No
suspend No Yes No
switch No Yes No
telltc No Yes No
test Yes No Yes
then No No Yes
time Yes Yes No
times No No Yes
trap No No Yes
true Yes No Yes
type No No Yes
ulimit No No Yes
umask No** Yes Yes
unalias No** Yes Yes
uncomplete No Yes No
unhash No Yes No
unlimit No Yes No
unset No Yes Yes
unsetenv No Yes No
until No No Yes
wait No** Yes Yes
where No Yes No
which Yes Yes No
while No Yes Yes